SF Expo was intended to be a professionally-run sf convention "a professional convention run by professionals" which was scheduled to be held in Manhattan at the New York Hilton hotel on June 25-29, 1976. It was intended to be annual, sometimes billing itself as "SF Expo '76". (Amusingly, their logo looked like it was "SEXpo".)

SF Expo caused enormous consternation in fandom, fearing that sf cons would be taken over by commercial interests. For example, close to half the October 1975 issue of Karass (#18) was devoted to it.

At first, SF Expo spoke of paying authors to speak and organizing charter flights to New York which would be hosted by pros. They also planned a convention prozine. But as the convention planning proceeded, these plans all seem to have been dropped.

It apparently badly over-reached and failed, and the convention was cancelled. According to reports, about six weeks before the convention, the New York Hilton informed them that because of the Star Trek convention fiasco, daily attendance would be limited to 8000 people (!). Since this was below what SF Expo planned for, they pulled out of the Hilton and tried to move to the New York Coliseum. They reported losing $37,000.

This caused their main backer to drop out and convention finances collapsed. For unknown reasons, they waited until just eight days before the scheduled convention to notify their members of the convention's cancellation — far too late for most of the foreign authors and fans who were coming.

They tried a second time and scheduled a convention (called the Playboy SF Convention, but known to some fans as Bunnycon) for October 22-25, 1976 at the Playboy Great Gorge Resort & Inn in near McAfee, New Jersey. They reported that attendance was 800 to 850, but these were mostly one-day memberships and chairmanJames Harvin reported that the convention lost "a considerable amount of money".

A report on the convention in Locus by Ginjer Buchanan said that the hotel was impressive, but poorly run and uncooperative with the convention. Programming was so-so with a lot of Star Trek convention-style one-person program items. The huckster room was only part-filled and 90% Star Trek (which was not a problem as there were few customers — some hucksters played frisbee in it.) There were no parties, but a great art show.

It's difficult to be sure, but this mess seems to have been the result of honest overshooting rather than fraud. But it was certainly a prime example of the mad optimism which sometimes infects novice con-runners.